Neptis hylas, sometimes known as the Common Sailer, is a species of nymphalid

Nymphalidae

The Nymphalidae is a family of about 5,000 species of butterflies which are distributed throughout most of the world. These are usually medium sized to large butterflies. Most species have a reduced pair of forelegs and many hold their colourful wings flat when resting. They are also called...

 butterfly

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 found in South Asia

South Asia

South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...

 and Southeast Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

. It has a characteristic stiff gliding flight achieved by short and shallow wingbeats just above the horizontal.

Description

Dry-season form - Upperside black, with pure white markings. Fore wing discoidal streak clavate, apically truncate, subapically either notched or sometimes indistinctly divided; triangular spot beyond broad, well-defined, acute at apex, but not elongate ; discal series of spots separate, not connate, each about twice as long as broad; postdiscal transverse series of small spots incomplete, but some are always present. Hind wing: subbasal band of even or nearly oven width ; discal and subterminal pale lines obscure; postdiscal series of spots well separated, quadrate or subquadrate, very seldom narrow. Underside from pale golden ochraceous to dark ochraceous almost chocolate ; white markings as on the upperside, but broader and defined in black. Fore wing: interspaces 1 a and 1 from base to near the apex shaded with black, some narrow transverse white markings on either side of the transverse postdiscal series of small spots. Hind wing a streak of white on costal margin at base, a more slender white streak below it; the discal and subterminal pale lines of the upperside replaced by narrow white lines with still narrower margins of black. Antennae, head, thorax and abdomen black; the palpi, thorax and abdomen beneath dusky white.
Wet-season form - Differs only in the narrowness of the white markings and in the slightly darker ground-colour and broader black margins to the spots and bands on the underside.

This species has been observed to make sounds whose function has not been established.

Distribution

Throughout continental India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

; Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

; Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

 ; Myanmar

Myanmar

Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

 ; Tenasserim, extending to China and Indomalaya

Indomalaya

The Indomalaya ecozone is one of the eight ecozones that cover the planet's land surface. It extends across most of South and Southeast Asia and into the southern parts of East Asia....

.

Larva

Race varmona = eurynome. Frederic Moore

Frederic Moore

Frederic Moore FZS was a British entomologist. It has been said that Moore was born at 33 Bruton Street but may be incorrect given that this was the address of the menagerie and office of the Zoological Society of London from 1826 to 1836.Moore was appointed an assistant in the East India Company...

 describes this from a drawing by Mr. S. N. Ward (Samuel Neville Ward) as follows :

"Head larger than anterior segment, vertex

Vertex (anatomy)

In arthropod and vertebrate anatomy, the vertex refers to the upper surface of the head.In humans, the vertex is formed by four bones of the skull: the frontal bone, the two parietal bones, and the occipital bone...

with two short pointed spines, cheeks obtusely spined; third, fourth, sixth and twelfth segments armed with a subdorsal pair of stout fleshy spiny processes, those on the fourth segment longest. Colour pale green ; face, tip of processes and segments slightly washed with pale pinkish, a slight pinkish oblique lateral fascia from anal process ; a small, dark, lateral spot on sixth segment."

Pupa

"Rather short; head-piece bluntly cleft in front, vertex pointed ; thorax dorsally prominent and angular ; dorsum angular at base ; abdominal segments slightly angled dorsally; wing-cases somewhat dilated laterally. Colour pale brownish ochreous, with lateral thoracic golden spots."